+++ /dev/null
-/*\r
-* Copyright 2007 ZXing authors\r
-*\r
-* Licensed under the Apache License, Version 2.0 (the "License");\r
-* you may not use this file except in compliance with the License.\r
-* You may obtain a copy of the License at\r
-*\r
-* http://www.apache.org/licenses/LICENSE-2.0\r
-*\r
-* Unless required by applicable law or agreed to in writing, software\r
-* distributed under the License is distributed on an "AS IS" BASIS,\r
-* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\r
-* See the License for the specific language governing permissions and\r
-* limitations under the License.\r
-*/\r
-namespace com.google.zxing.qrcode.detector\r
-{\r
- using System;\r
- using com.google.zxing;\r
- using com.google.zxing.common;\r
-\r
- public sealed class FinderPatternFinder\r
- { \r
- private static int CENTER_QUORUM = 2;\r
- private static int MIN_SKIP = 3; // 1 pixel/module times 3 modules/center\r
- private static int MAX_MODULES = 57; // support up to version 10 for mobile clients\r
- private static int INTEGER_MATH_SHIFT = 8;\r
-\r
- private MonochromeBitmapSource image;\r
- private System.Collections.ArrayList possibleCenters;\r
- private bool hasSkipped;\r
- private int[] crossCheckStateCount;\r
-\r
- /**\r
- * <p>Creates a finder that will search the image for three finder patterns.</p>\r
- *\r
- * @param image image to search\r
- */\r
- public FinderPatternFinder(MonochromeBitmapSource image) {\r
- this.image = image;\r
- this.possibleCenters = new System.Collections.ArrayList();\r
- this.crossCheckStateCount = new int[5];\r
- }\r
-\r
- public FinderPatternInfo find(System.Collections.Hashtable hints) {\r
- bool tryHarder = hints != null && hints.ContainsKey(DecodeHintType.TRY_HARDER);\r
- int maxI = image.getHeight();\r
- int maxJ = image.getWidth();\r
- // We are looking for black/white/black/white/black modules in\r
- // 1:1:3:1:1 ratio; this tracks the number of such modules seen so far\r
-\r
- // Let's assume that the maximum version QR Code we support takes up 1/4 the height of the\r
- // image, and then account for the center being 3 modules in size. This gives the smallest\r
- // number of pixels the center could be, so skip this often. When trying harder, look for all\r
- // QR versions regardless of how dense they are.\r
- int iSkip = (int) (maxI / (MAX_MODULES * 4.0f) * 3);\r
- if (iSkip < MIN_SKIP || tryHarder) {\r
- iSkip = MIN_SKIP;\r
- }\r
-\r
- bool done = false;\r
- int[] stateCount = new int[5];\r
- BitArray blackRow = new BitArray(maxJ);\r
- for (int i = iSkip - 1; i < maxI && !done; i += iSkip) {\r
- // Get a row of black/white values\r
- blackRow = image.getBlackRow(i, blackRow, 0, maxJ);\r
- stateCount[0] = 0;\r
- stateCount[1] = 0;\r
- stateCount[2] = 0;\r
- stateCount[3] = 0;\r
- stateCount[4] = 0;\r
- int currentState = 0;\r
- for (int j = 0; j < maxJ; j++) {\r
- if (blackRow.get(j)) {\r
- // Black pixel\r
- if ((currentState & 1) == 1) { // Counting white pixels\r
- currentState++;\r
- }\r
- stateCount[currentState]++;\r
- } else { // White pixel\r
- if ((currentState & 1) == 0) { // Counting black pixels\r
- if (currentState == 4) { // A winner?\r
- if (foundPatternCross(stateCount)) { // Yes\r
- bool confirmed = handlePossibleCenter(stateCount, i, j);\r
- if (confirmed) {\r
- // Start examining every other line. Checking each line turned out to be too\r
- // expensive and didn't improve performance.\r
- iSkip = 2;\r
- if (hasSkipped) {\r
- done = haveMulitplyConfirmedCenters();\r
- } else {\r
- int rowSkip = findRowSkip();\r
- if (rowSkip > stateCount[2]) {\r
- // Skip rows between row of lower confirmed center\r
- // and top of presumed third confirmed center\r
- // but back up a bit to get a full chance of detecting\r
- // it, entire width of center of finder pattern\r
-\r
- // Skip by rowSkip, but back off by stateCount[2] (size of last center\r
- // of pattern we saw) to be conservative, and also back off by iSkip which\r
- // is about to be re-added\r
- i += rowSkip - stateCount[2] - iSkip;\r
- j = maxJ - 1;\r
- }\r
- }\r
- } else {\r
- // Advance to next black pixel\r
- do {\r
- j++;\r
- } while (j < maxJ && !blackRow.get(j));\r
- j--; // back up to that last white pixel\r
- }\r
- // Clear state to start looking again\r
- currentState = 0;\r
- stateCount[0] = 0;\r
- stateCount[1] = 0;\r
- stateCount[2] = 0;\r
- stateCount[3] = 0;\r
- stateCount[4] = 0;\r
- } else { // No, shift counts back by two\r
- stateCount[0] = stateCount[2];\r
- stateCount[1] = stateCount[3];\r
- stateCount[2] = stateCount[4];\r
- stateCount[3] = 1;\r
- stateCount[4] = 0;\r
- currentState = 3;\r
- }\r
- } else {\r
- stateCount[++currentState]++;\r
- }\r
- } else { // Counting white pixels\r
- stateCount[currentState]++;\r
- }\r
- }\r
- }\r
- if (foundPatternCross(stateCount)) {\r
- bool confirmed = handlePossibleCenter(stateCount, i, maxJ);\r
- if (confirmed) {\r
- iSkip = stateCount[0];\r
- if (hasSkipped) {\r
- // Found a third one\r
- done = haveMulitplyConfirmedCenters();\r
- }\r
- }\r
- }\r
- }\r
-\r
- FinderPattern[] patternInfo = selectBestPatterns();\r
- GenericResultPoint.orderBestPatterns(patternInfo);\r
-\r
- return new FinderPatternInfo(patternInfo);\r
- }\r
-\r
- /**\r
- * Given a count of black/white/black/white/black pixels just seen and an end position,\r
- * figures the location of the center of this run.\r
- */\r
- private static float centerFromEnd(int[] stateCount, int end) {\r
- return (float) (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0f;\r
- }\r
-\r
- /**\r
- * @param stateCount count of black/white/black/white/black pixels just read\r
- * @return true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios\r
- * used by finder patterns to be considered a match\r
- */\r
- private static bool foundPatternCross(int[] stateCount) {\r
- int totalModuleSize = 0;\r
- for (int i = 0; i < 5; i++) {\r
- int count = stateCount[i];\r
- if (count == 0) {\r
- return false;\r
- }\r
- totalModuleSize += count;\r
- }\r
- if (totalModuleSize < 7) {\r
- return false;\r
- }\r
- int moduleSize = (totalModuleSize << INTEGER_MATH_SHIFT) / 7;\r
- int maxVariance = moduleSize / 2;\r
- // Allow less than 50% variance from 1-1-3-1-1 proportions\r
- return Math.Abs(moduleSize - (stateCount[0] << INTEGER_MATH_SHIFT)) < maxVariance &&\r
- Math.Abs(moduleSize - (stateCount[1] << INTEGER_MATH_SHIFT)) < maxVariance &&\r
- Math.Abs(3 * moduleSize - (stateCount[2] << INTEGER_MATH_SHIFT)) < 3 * maxVariance &&\r
- Math.Abs(moduleSize - (stateCount[3] << INTEGER_MATH_SHIFT)) < maxVariance &&\r
- Math.Abs(moduleSize - (stateCount[4] << INTEGER_MATH_SHIFT)) < maxVariance;\r
- }\r
-\r
- private int[] getCrossCheckStateCount() {\r
- crossCheckStateCount[0] = 0;\r
- crossCheckStateCount[1] = 0;\r
- crossCheckStateCount[2] = 0;\r
- crossCheckStateCount[3] = 0;\r
- crossCheckStateCount[4] = 0;\r
- return crossCheckStateCount;\r
- }\r
-\r
- /**\r
- * <p>After a horizontal scan finds a potential finder pattern, this method\r
- * "cross-checks" by scanning down vertically through the center of the possible\r
- * finder pattern to see if the same proportion is detected.</p>\r
- *\r
- * @param startI row where a finder pattern was detected\r
- * @param centerJ center of the section that appears to cross a finder pattern\r
- * @param maxCount maximum reasonable number of modules that should be\r
- * observed in any reading state, based on the results of the horizontal scan\r
- * @return vertical center of finder pattern, or {@link Float#NaN} if not found\r
- */\r
- private float crossCheckVertical(int startI, int centerJ, int maxCount, int originalStateCountTotal) {\r
- MonochromeBitmapSource image = this.image;\r
-\r
- int maxI = image.getHeight();\r
- int[] stateCount = getCrossCheckStateCount();\r
-\r
- // Start counting up from center\r
- int i = startI;\r
- while (i >= 0 && image.isBlack(centerJ, i)) {\r
- stateCount[2]++;\r
- i--;\r
- }\r
- if (i < 0) {\r
- return float.NaN;\r
- }\r
- while (i >= 0 && !image.isBlack(centerJ, i) && stateCount[1] <= maxCount) {\r
- stateCount[1]++;\r
- i--;\r
- }\r
- // If already too many modules in this state or ran off the edge:\r
- if (i < 0 || stateCount[1] > maxCount) {\r
- return float.NaN;\r
- }\r
- while (i >= 0 && image.isBlack(centerJ, i) && stateCount[0] <= maxCount) {\r
- stateCount[0]++;\r
- i--;\r
- }\r
- if (stateCount[0] > maxCount) {\r
- return float.NaN;\r
- }\r
-\r
- // Now also count down from center\r
- i = startI + 1;\r
- while (i < maxI && image.isBlack(centerJ, i)) {\r
- stateCount[2]++;\r
- i++;\r
- }\r
- if (i == maxI) {\r
- return float.NaN;\r
- }\r
- while (i < maxI && !image.isBlack(centerJ, i) && stateCount[3] < maxCount) {\r
- stateCount[3]++;\r
- i++;\r
- }\r
- if (i == maxI || stateCount[3] >= maxCount) {\r
- return float.NaN;\r
- }\r
- while (i < maxI && image.isBlack(centerJ, i) && stateCount[4] < maxCount) {\r
- stateCount[4]++;\r
- i++;\r
- }\r
- if (stateCount[4] >= maxCount) {\r
- return float.NaN;\r
- }\r
-\r
- // If we found a finder-pattern-like section, but its size is more than 20% different than\r
- // the original, assume it's a false positive\r
- int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];\r
- if (5 * Math.Abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {\r
- return float.NaN;\r
- }\r
-\r
- return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : float.NaN;\r
- }\r
-\r
- /**\r
- * <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,\r
- * except it reads horizontally instead of vertically. This is used to cross-cross\r
- * check a vertical cross check and locate the real center of the alignment pattern.</p>\r
- */\r
- private float crossCheckHorizontal(int startJ, int centerI, int maxCount, int originalStateCountTotal) {\r
- MonochromeBitmapSource image = this.image;\r
-\r
- int maxJ = image.getWidth();\r
- int[] stateCount = getCrossCheckStateCount();\r
-\r
- int j = startJ;\r
- while (j >= 0 && image.isBlack(j, centerI)) {\r
- stateCount[2]++;\r
- j--;\r
- }\r
- if (j < 0) {\r
- return float.NaN;\r
- }\r
- while (j >= 0 && !image.isBlack(j, centerI) && stateCount[1] <= maxCount) {\r
- stateCount[1]++;\r
- j--;\r
- }\r
- if (j < 0 || stateCount[1] > maxCount) {\r
- return float.NaN;\r
- }\r
- while (j >= 0 && image.isBlack(j, centerI) && stateCount[0] <= maxCount) {\r
- stateCount[0]++;\r
- j--;\r
- }\r
- if (stateCount[0] > maxCount) {\r
- return float.NaN;\r
- }\r
-\r
- j = startJ + 1;\r
- while (j < maxJ && image.isBlack(j, centerI)) {\r
- stateCount[2]++;\r
- j++;\r
- }\r
- if (j == maxJ) {\r
- return float.NaN;\r
- }\r
- while (j < maxJ && !image.isBlack(j, centerI) && stateCount[3] < maxCount) {\r
- stateCount[3]++;\r
- j++;\r
- }\r
- if (j == maxJ || stateCount[3] >= maxCount) {\r
- return float.NaN;\r
- }\r
- while (j < maxJ && image.isBlack(j, centerI) && stateCount[4] < maxCount) {\r
- stateCount[4]++;\r
- j++;\r
- }\r
- if (stateCount[4] >= maxCount) {\r
- return float.NaN;\r
- }\r
-\r
- // If we found a finder-pattern-like section, but its size is significantly different than\r
- // the original, assume it's a false positive\r
- int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];\r
- if (5 * Math.Abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {\r
- return float.NaN;\r
- }\r
-\r
- return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : float.NaN;\r
- }\r
-\r
- /**\r
- * <p>This is called when a horizontal scan finds a possible alignment pattern. It will\r
- * cross check with a vertical scan, and if successful, will, ah, cross-cross-check\r
- * with another horizontal scan. This is needed primarily to locate the real horizontal\r
- * center of the pattern in cases of extreme skew.</p>\r
- *\r
- * <p>If that succeeds the finder pattern location is added to a list that tracks\r
- * the number of times each location has been nearly-matched as a finder pattern.\r
- * Each additional find is more evidence that the location is in fact a finder\r
- * pattern center\r
- *\r
- * @param stateCount reading state module counts from horizontal scan\r
- * @param i row where finder pattern may be found\r
- * @param j end of possible finder pattern in row\r
- * @return true if a finder pattern candidate was found this time\r
- */\r
- private bool handlePossibleCenter(int[] stateCount,\r
- int i,\r
- int j) {\r
- int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];\r
- float centerJ = centerFromEnd(stateCount, j);\r
- float centerI = crossCheckVertical(i, (int) centerJ, stateCount[2], stateCountTotal);\r
- if (!Single.IsNaN(centerI)) {\r
- // Re-cross check\r
- centerJ = crossCheckHorizontal((int) centerJ, (int) centerI, stateCount[2], stateCountTotal);\r
- if (!Single.IsNaN(centerJ))\r
- {\r
- float estimatedModuleSize = (float) stateCountTotal / 7.0f;\r
- bool found = false;\r
- int max = possibleCenters.Count;\r
- for (int index = 0; index < max; index++) {\r
- FinderPattern center = (FinderPattern) possibleCenters[index];\r
- // Look for about the same center and module size:\r
- if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {\r
- center.incrementCount();\r
- found = true;\r
- break;\r
- }\r
- }\r
- if (!found) {\r
- possibleCenters.Add(new FinderPattern(centerJ, centerI, estimatedModuleSize));\r
- }\r
- return true;\r
- }\r
- }\r
- return false;\r
- }\r
-\r
- /**\r
- * @return number of rows we could safely skip during scanning, based on the first\r
- * two finder patterns that have been located. In some cases their position will\r
- * allow us to infer that the third pattern must lie below a certain point farther\r
- * down in the image.\r
- */\r
- private int findRowSkip() {\r
- int max = possibleCenters.Count;\r
- if (max <= 1) {\r
- return 0;\r
- }\r
- FinderPattern firstConfirmedCenter = null;\r
- for (int i = 0; i < max; i++) {\r
- FinderPattern center = (FinderPattern) possibleCenters[i];\r
- if (center.getCount() >= CENTER_QUORUM) {\r
- if (firstConfirmedCenter == null) {\r
- firstConfirmedCenter = center;\r
- } else {\r
- // We have two confirmed centers\r
- // How far down can we skip before resuming looking for the next\r
- // pattern? In the worst case, only the difference between the\r
- // difference in the x / y coordinates of the two centers.\r
- // This is the case where you find top left last.\r
- hasSkipped = true;\r
- return (int) (Math.Abs(firstConfirmedCenter.getX() - center.getX()) -\r
- Math.Abs(firstConfirmedCenter.getY() - center.getY())) / 2;\r
- }\r
- }\r
- }\r
- return 0;\r
- }\r
-\r
- /**\r
- * @return true iff we have found at least 3 finder patterns that have been detected\r
- * at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the\r
- * candidates is "pretty similar"\r
- */\r
- private bool haveMulitplyConfirmedCenters() {\r
- int confirmedCount = 0;\r
- float totalModuleSize = 0.0f;\r
- int max = possibleCenters.Count;\r
- for (int i = 0; i < max; i++) {\r
- FinderPattern pattern = (FinderPattern) possibleCenters[i];\r
- if (pattern.getCount() >= CENTER_QUORUM) {\r
- confirmedCount++;\r
- totalModuleSize += pattern.getEstimatedModuleSize();\r
- }\r
- }\r
- if (confirmedCount < 3) {\r
- return false;\r
- }\r
- // OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive"\r
- // and that we need to keep looking. We detect this by asking if the estimated module sizes\r
- // vary too much. We arbitrarily say that when the total deviation from average exceeds\r
- // 15% of the total module size estimates, it's too much.\r
- float average = totalModuleSize / max;\r
- float totalDeviation = 0.0f;\r
- for (int i = 0; i < max; i++) {\r
- FinderPattern pattern = (FinderPattern) possibleCenters[i];\r
- totalDeviation += Math.Abs(pattern.getEstimatedModuleSize() - average);\r
- }\r
- return totalDeviation <= 0.15f * totalModuleSize;\r
- }\r
-\r
- /**\r
- * @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are\r
- * those that have been detected at least {@link #CENTER_QUORUM} times, and whose module\r
- * size differs from the average among those patterns the least\r
- * @throws ReaderException if 3 such finder patterns do not exist\r
- */\r
- private FinderPattern[] selectBestPatterns(){\r
- Collections.insertionSort(possibleCenters, new CenterComparator());\r
- int size = 0;\r
- int max = possibleCenters.Count;\r
- while (size < max) {\r
- if (((FinderPattern) possibleCenters[size]).getCount() < CENTER_QUORUM) {\r
- break;\r
- }\r
- size++;\r
- }\r
-\r
- if (size < 3) {\r
- // Couldn't find enough finder patterns\r
- throw new ReaderException();\r
- }\r
-\r
- if (size > 3) {\r
- // Throw away all but those first size candidate points we found.\r
- SupportClass.SetCapacity(possibleCenters, size);\r
- // We need to pick the best three. Find the most\r
- // popular ones whose module size is nearest the average\r
- float averageModuleSize = 0.0f;\r
- for (int i = 0; i < size; i++) {\r
- averageModuleSize += ((FinderPattern) possibleCenters[i]).getEstimatedModuleSize();\r
- }\r
- averageModuleSize /= (float) size;\r
- // We don't have java.util.Collections in J2ME\r
- Collections.insertionSort(possibleCenters, new ClosestToAverageComparator(averageModuleSize));\r
- }\r
-\r
- return new FinderPattern[]{\r
- (FinderPattern) possibleCenters[0],\r
- (FinderPattern) possibleCenters[1],\r
- (FinderPattern) possibleCenters[2]\r
- };\r
- }\r
-\r
- /**\r
- * <p>Orders by {@link FinderPattern#getCount()}, descending.</p>\r
- */\r
- private class CenterComparator : Comparator {\r
- public int compare(object center1, object center2)\r
- {\r
- return ((FinderPattern) center2).getCount() - ((FinderPattern) center1).getCount();\r
- }\r
- }\r
-\r
- /**\r
- * <p>Orders by variance from average module size, ascending.</p>\r
- */\r
- private class ClosestToAverageComparator : Comparator {\r
- private float averageModuleSize;\r
-\r
- public ClosestToAverageComparator(float averageModuleSize) {\r
- this.averageModuleSize = averageModuleSize;\r
- }\r
-\r
- public int compare(object center1, object center2)\r
- {\r
- return Math.Abs(((FinderPattern) center1).getEstimatedModuleSize() - averageModuleSize) <\r
- Math.Abs(((FinderPattern) center2).getEstimatedModuleSize() - averageModuleSize) ?\r
- -1 :\r
- 1;\r
- }\r
- }\r
-\r
- }\r
-\r
-}
\ No newline at end of file
projects / zxing.git / blobdiff